Mine roof supports



1965 J. D. KIBBLE ETAL 3,215,201

MINE ROOF SUPPORTS I Filed Oct. 7, 1960 2 Sheets-Sheet 1 FIG. 2.

FIG. I.

171 vehfbr John Du nbar Klbble Mar-3m; James WI'I I' 'S Nov. 9, 1965 J.D. KIBBLE ETAL 3,216,201

MINE ROOF SUPPORTS Filed Oct. 7. 1960 2 Sheets-Sheet 2 FIG. 3.

In V8 n 'OI'S K mm D. mu

J Morgan Hiams United States Fatent O 3,216,201 MINE RGGF SUPPORTS JohnDunbar Kibhle, London, and Morgan James Williams, Harmondsworth, WestDrayton, England, assignors to Coal Industry (Patents) Limited, London,

England, a company of Great Britain Filed Oct. 7, 1960, Ser. No. 61,210Claims priority, application Great Britain, Oct. 12, 1959, 34,500/59;June 16, 196i), 21,211/60 9 Claims. (CI. 61-45) This invention relatesto mine roof support systems.

The present invention provides a mine roof support system comprising aplurality of mine roof supports advanceable in a predetermined sequence,in which the arrangement is such that in operation of the system theoperation of the next support to be advanced is initiated by a signalpassed to that support automatically upon completion of operation of thepreceding support in the sequence.

Preferably, the arrangement is such that the signal is only passed onautomatically to the next support to be advanced when the precedingsupport has been proved fully re-set against the roof and/ or such thatthe signal is only passed on automatically to the next support to beadvanced when the preceding support has been proved to be advanced by apredetermined amount.

The signal may be constituted by a fluid pressure or by an electricalsignal.

One embodiment of the invention will now be described in greater detail,by way of exam le only, with reference to the accompanying drawings, ofwhich:

FIGURES 1 and 2 being partly sectional and diagrammatic end and sideelevations respectively of part of an arrangement according to theinvention, and

FIGURE 3 is a diagram showing a section of a hydraulic circuit.

In FIGURES 1 and 2 is shown a hydraulic self-advancing mine roof supportunit which is one of a plurality (the others not being shown) linked toan armoured flexible face conveyor.

FIGURE 1 is a view in a direction parallel to the coal face, and FIGURE2 which is an end elevation at right angles to the coal face lookingtowards the unexcavated coal. The unit consists of a base 1 upon whichare mounted resiliently two single acting hydraulic jacks, 2 and 3,which will be termed legs. A roof bar 4 is mounted, also resiliently,upon the legs 2 and '3. Within the base 1 a double-acting hydrauliccylinder 5 is mounted in a gimbal bearing 6 which permits a limitedamount of angular movement of the cylinder 5. The piston rod 7 of thecylinder 5 is connected by means of a pin 8 and a bracket 9 to thearmoured flexible face conveyor 10. The conveyor carries a spill plate11 upon which are mounted at intervals brackets 12 which carry theflexible pipes 13 passing along the length of the face. The pipes 13 areconnected to each support unit by branch flexible pipes as may berequired. A hydraulic valve block 14 is mounted in a suitable positionon the base. This is connected with the cylinder 5 and the legs 2 and 3by pipes which are not shown. Similar support units are placed at shortintervals throughout the length of a long wall coal face.

The manual operation of this will now be described. After a web of coalhas been cut and loaded on to the conveyor hydraulic pressure is appliedto the cylinder 5 in such a way as to cause the rod 7 to be pushed out.At the same time the other support units are Operated similarly. Thiswill cause the conveyor to move forward into the space vacated by thecut coal. It may only be necessary to push the conveyor with thecylinder of a proportion of the support units. The support units arethen moved forward one at a time in sequence along the face by means oflowering the legs of each, and reversing the hydraulic pressureconnections to the cylinder 5 so that the rod 7 is pulled in. As theconveyor will be held in position by the pushing action of adjacentsupport units this operation will cause the support unit in question tomove forward until its cylinder 5 is fully contracted. Hydraulicpressure is then re-applied to the legs 2 and 3 so that they extenduntil the roof bar 4 is forced against the roof. The hydraulicconnection to the cylinder 5 are then reversed so that it resumespushing against the conveyor. The next support unit may then be lowered,advanced, and reset similarly, but it is imperative for reasons ofsafety that no unit is lowered from the roof unless the adjacent one hasbeen reset.

The means by which these operations may be perform-ed without manualintervention is shown in FIG- URE 3 which is a diagram of the fluidpressure operated equipment of three adjacent support units in thesystem. These three units and their associated equipment are identicalto each other both in construction and in operation. For this reason itis considered necessary only to describe in detail the operation andconstruction of one of them. For convenience the center support unitwill be described. The elements of the left and right hand support unitstogether with the associated equipment are respectively identified inthe drawing by using the letters A or B with the reference numeralsemployed for describing the center unit and its associated equipment. InFIGURE 3 the legs of the support unit are shown at 2 and 3 and itshorizontal cylinder at 5. The necessary valves may be constructed in oneblock represented by the dotted line 15, except for the valve 16, whichis mounted on the rear end of the cylinder 5, and is also shown inFIGURE 1. The flexible pipe running along the face conveying hydraulicfluid from the pump is shown at 17 and that returning fluid to the tankat 18. Two additional flexible pipes 19 and 20 are also required.

In the normal state of the circuit only the pipe 17, has fluid pressureapplied to it. Thi pressure is fed through the non-return valve 21 tothe leg control valve 22, which is a 3-ported two-position valve springloaded into the hydraulic position shown in which the hydraulic pressureis allowed to pass through the connection 23 to the legs 2 and 3. Ifconvergence of the roof should take place the fluid contained in thelegs 2 and 3 cannot return to the line 17 because of the action of thevalve 21. The pressure is therefore built up until it is sufficient tooperate a relief valve 24 through which the fluid escapes to a reservoiror to waste.

The cylinder 5 is controlled by means of the hydraulic valve 25, whichis a 5-ported two-position valve normally held by a spring in theposition shown in which the pump pressure, though applied to port 26 ofthe valve 25, is there sealed off.

When it is desired to advance the conveyor, pressure is applied to thepipe 19, and the valve 25 allows this pressure to pass through to theend 27 of the cylinder 5 to cause extension of the piston rod. Thepurpose of the separate pressure line 19 is to permit control of thepressure with which the conveyor is advanced, as'is required for certainmining operations such as the use of coal ploughs. If this is notdesired the port 28 may be connected to the main pressure line 17instead of to the pipe 19.

When it is desired to advance the support units, fluid pressure isapplied to the pipe 20. This pressure is applied to a pilot cylinder 29of the valve 22, causing it to move to its alternative position in whichthe legs are connected through the port 30 to the return line 18, thuspermitting them to lower. The pilot pressure is also applied to thecylinder 31 of the valve 25 causing it to move to its alternativeposition in which the pushing side 27 of the cylinder is connectedthroughthe port 32 of the valve 25 to the return line 18; the port 28 issealed to cut off the pressure supplied by the line 19; and also theother end 33 of the cylinder 5, previously connected through the ports34 and 32 of the valve 25 to the return line 18, is then connectedthrough the port 26 to the pump pressure in the main pipe 17.

Therefore, at the same time the legs are lowered from the roof and thesupport unit is brought forward.

Pressure in the pilot line 20 is also connected to the port 35 of thevalve 16. This valve is a fluid flow shutoft valve in the form of a3-ported two-position valve having a shut-off member in the form of adouble landed spool which is normally held by a spring in the positionshown, but when, as the support unit is being pulled forward, the pistonof the cylinder 5 nears the end of its travel it strikes the plunger 36forcing the valve 16 into its alternative position. Connection is thenestablished from the port 35 to the port 37 previously connected toatmosphere through port 48. The port 37 is connected to a further pilotcylinder '39, of the valve 22. The piston of the cylinder 39 has an areaequal to or greater than that of the pilot cylinder 29. Therefore thevalve 22 will be restored to its initial position.

Therefore, when the support unit has been pulled forward to the limit ofits travel pressure is re-applied to the legs so that they are resetagainst the roof.

Pilot pressure from the port 37 is also applied through the port 40 tothe valve 41. This is a fluid flow shut-off valve in the form of a3-ported two-position valve having a shut-off member in the form of adouble landed spool which is normally held by a strong spring in theposition shown. The valve is operated by fluid pressure from the legs ofthe support unit being applied to the pilot cylinder .42. Thecharacteristic of the valve 41 is such that it will move to itsalternative position when the pressure in the cylinder 42 approachesthat supplied through the line 17 by the main pump. Thus, when the legsof the unit are completely reset, the valve 41 will operate, connectingthe port 40 to the port 43. This port is connected to a second pilotcylinder 44, of the valve 25. This cylinder has an area equal to orgreater than that of the pilot cylinder 31, so that the valve 25 isrestored to its initial position, restoring the original pressureconnections to the cylinder 5.

The support unit has now completed its advancing operation. The port 43of the valve 41 is also connected to the flexible pipe 45, which passesalong the face to connect with the pipe 20B of the adjacent (right handside) support unit, where it fulfils a function like that of the pipe 20in conveying pilot fluid pressure to initiate the operation of thatsupport unit. It will be noted that this cannot occur until the centerunit whose operation has been described has completed its forwardmotion, as indicated by operation of the valve 16, and ha been resetagainst the roof as indicated by the operation of the valve 41. Thesafety requirements are thus fulfilled. If it is desired to operate thesupport unit manually, this may be done by operating the valve 22directly by means of the screw 46 or the valve 25 by means of the screw47.

It is to be understood that the equipment described is only one exampleof that which could be used and the principle described may have otherembodiments.

Thus the invention is applicable to support units with only one leg orto those with more than two. If it is desired to divide the legs of theunit into two or more hydraulically independent groups, this may be doneby providing for each group a further set ofvalves equivalent to valvesnumbers 21, 22 and 24 in FIGURE 3. It should only be necessary toprovide one valve 41.

Support systems of the kind in which the units are of more than one typemay also be operated by an adaptation of the principle which has beendescribed. For example, the pilot pipe 45, may be connected, not to theimmediately adjacent unit, but to the adjacent unit of the same type.For each other type of unit a further system of pilot pipescorresponding to 20 and 45 is then provided.

Further, the valves are represented in the diagram as slide valves onlyfor clarity, and may in fact alternatively be rotary or poppet valves.

In a practical example the main pump supplies a hydraulic fluidconsisting of an emulsion of Water with 2% of soluble oil at 1,000p.s.i. and the relief valve 24, are set to open at 10,000 p.s.i. Thepressure to advance the conveyor applied to the pipe 19, is adjustablebetween and 500 p.s.i. and is not applied to all support units but onlyto those at 10 yard intervals. The pilot pressure applied to the pipe20, is also a water and soluble oil emulsion at 1,000 p.s.i.Alternatively compressed air at 70 p.s.i. has been used. The valves areof the multiple poppet type.

If desired, the above described roof support system may include in eachsupport unit the arrangement described and claimed in our co-pendingapplication, Serial No. 57,462, filed September 21, 1960, now Patent No.3,120,105, whereby the extent of lowering of the legs of the unit iscontrolled in accordance with the resistance to advance of the unit.

It will be appreciated that the above described arrangement does notprovide for snaking of the conveyor as is customary with machines suchas shearers and trepanners under conventional manual control. If thesystem is used with such machines it is necessary to adopt thealternative to snaking, namely, that the conveyor advancing pressureconduit is divided into sections which are controlled by valvescontrolling the admission of pressure fluid. After the coal-winningmachine has traversed a certain section of the face, the conveyor in thewhole of that section may be advanced by manual or remote operation ofthe appropriate valve. The support units in that section may then beoperated remotely.

When the pressure in the legs 2 and 3 reaches a value indicative oftheir being adequately set against the roof, the pressure switch 68operates to move its contacts from the position shown in FIGURE 4 intothe position in which the supply of current to the coil 70 of valve 51is cut off (by opening of contact 69) and (by closing of contact 67)current to initiate operation of the next succeeding support is passedto that support over lead 71, this current energising the valves 50 and51 of the next succeeding support.

This arrangement of FIGURES 4 and 5 shows the electrical circuit of thesupports arranged in series along the face but, if desired, thisarrangement may be modified by referring back to a control panel theelectric connections to the solenoid valves and to limit switch and thepressure switch. There is then the great advantage of being able, fromthe control point, to observe the position and the leg pressure of eachsupport unit and of being able to control each operation individually ifdesired.

The system has, however, the disadvantage of requiring two solenoidvalves per support unit. This may be expensive and, particularly, it mayprevent the use of intrinsically safe electric circuits as the power required may be too high.

These disadvantages can be avoided by the use of the circuit shown inFIGURE 7.

Further embodiments of the present invention Will now be described ingreater detail, by way of example only, with reference to theaccompanying drawings, of which:

FIGURE 6 is a diagram of parts of an electro-hydraulic controlarrangement for a mine roof support unit of the kind referred to to beoperated at a plough face as referred to above,

FIGURE 7 is a diagram similar to FIGURE 6 of a modified controlarrangement,

FIGURE 8 is a diagram similar to FIGURE 6 of another modified controlarrangement suitable for a roof support unit employed at a shearer faceas referred to above, and

FIGURES 9 and 10 are electrical circuits suitable for use with thearrangement of FIGURES 6 and 7 and FIG- URE 8 respectively.

Referring to FIGURE 6, the diagram includes the double-acting horizontalhydraulic ram comprising a cylinder 5 accommodating a piston rod 102connected pivotally to an armoured flexible face conveyor (not shown).Two legs 2 and 3 of the roof support unit are indicated, but it will berealised that each such unit may comprise any desired number of legs.Extending along the length of the face are a main pressure flexible hose17, a return flexible hose 18, and a conveyor advancing pressureflexible hose 19. A hydraulic valve block is connected to both ends ofthe cylinder 5 and to the legs 2 and 3 and to the flexible hoses 17, 18and 19 by flexible branch pipes indicated by single lines. Asolenoid-operated valve 163 is connected in an appropriate electricalcircuit shown in FIGURE 9, the circuit also including a limit switch 57and a pressure switch 68 whose functions are similar to the equivalentswitches shown in FIGURE 5. The control arrangement also comprises ahydraulic leg control valve 22, a hydraulic ram control valve 120, ahydraulic leg relief valve 24, and a non-return valve 21.

The various valves 103, 22, 126, 24 and 22 may either be formed ininternal passages of the block 15 or they may have separate bodiesmounted on block 15.

The solenoid valve 103 is of similar construction as valves 56 and 51 ofFIGURES 4 and 5 and controls the application of a pilot pressure to thehydraulic valves 22 and 121). The valve 103 is a two-position,threeported valve, and in its normal de-energised state, the output port52 is connected to the return port 53 and the input port 54 is blocked.On the solenoid becoming energised, the valve 1113 operates so that theinput port 54 is connected to the output port 52 and the return port 53becomes blocked. This then allows a pilot pressure from line 17 to beapplied to the pilot cylinders 29 and 121 of the hydraulic valves 22 and120.

The hydraulic leg control valve 22, which controls the raising andlowering of the legs 2 and 3 and also returns the hydraulic valve 120 toits normal position, is a two-position valve with three main ports andone pilot port. In the normal position of the valve 22 the input port1194 is connected to the output port 165 and thence to the legs 2 and 3,and also to a pilot port 1116 of the hydraulic valve 120. On applying apilot pressure to the pilot cylinder 29, the valve 22 operates so thatthe input port 1134 becomes blocked and the output port 105 is connectedto a return port 107. This allows the pressure in the legs 2 and 3 andthe pressure of pilot port 106 on hydraulic valve 126 to be released. Onreleasing the pilot pressure from pilot cylinder 39, a spring 1113returns the valve 22 to its normal position.

The hydraulic ram control valve 120 which cont-rols the action of thedouble-acting cylinder 5, is a two-position valve with five main portsand three pilot ports. In its normal position the conveyor advancingpressure input port 1119 is connected to the output port 111) and thenceto the pushing port 111 of the cylinder 5. At the same time, the pullingport 112 of the cylinder 5 is connected to the return port 113, via theoutput port 114. On applying a pilot pressure to the pilot cylinder 121,the valve 120 operates (so long as pressure is not applied to pilot port106 at the same time) so that the conveyor advancing pressure input port109 becomes blocked and the output port 116 is connected to the returnport 113. This will stop the pushing forward of the face conveyor. Atthe same time the main pressure input port is connected to the outputport 114 and thence to the pulling port 112 of the cylinder. This allowsthe roof support unit to be pulled forward. The output port 114 is alsoconnected to the pilot port 116. This allows the valve 25 to be kept inits operated position after the pilot pressure at pilot cylinder 121 hasbeen released. This is known as self-holding. The valve will remain inits operated position until the pressure at the pilot port 1116 createsa force great enough to overcome that due to pressure at the pilot port116. The valve 120 will then return to its normal position.

The electrical circuit of the above described apparatus is shown in theaccompanying FIGURE 9 and includes in addition to the coil 122 of thevalve 103 a limit switch 57 similar to the limit switch 57 of FIGURE 4and a pressure switch 68 similar to the pressure switch 68 of FIGURE 4but having only a single contact 123 instead of the double contacts 67and 69.

The operation of the whole circuit can now be described. With the valves103, 22 and 120 in their normal position, it can be seen that theconveyor advancing pressure from the hose 19 is applied to the pushingport 111 of the cylinder 5 and that the main pressure from the hose 17is applied to the legs 2 and 3 and to the pilot port 106 of thehydraulic valve 121). When it is desired to move the roof support unitforward, the solenoid valve 103 is energised by closing switch 62(FIGURE 9). On becoming energised, the solenoid valve 103 supplies apilot pressure to the pilot cylinder 29 of the leg control valve 22 andto the pilot cylinder 121 of the ram control valve 129. This pilotpressure operates the leg control valve 22 which releases the pressurefrom the legs 2 and 3 and also from the pilot port 106 of ram controlvalve 120. The ram control valve 121? now operates, which allows themain pressure to flow to the pulling port 112 of the cylinder 5, andthis will pull the roof support unit forward. After the roof supportunit has moved forward to its required position, the limit switch 57(FIGURE 9) is operated so that the solenoid valve 103 is de-energised bythe opening of contact 58 of switch 57. This allows the leg controlvalve 22 to return to its normal position and thus re-apply pressure tothe legs 2 and 3. The ram control valve 120 remains in its operatedposition, because of its self-holding feature on pilot port 116 andcontinues to give the cylinder 5 a pulling force until the legs 2 and 3come into contact with the roof. As the legs 2 and 3 come into contactwith the roof, pressure at pilot port 106 of the ram control valve 120builds up and returns the ram control valve 120 to its normal position(ie, supplying conveying advancing pressure from line 19 to the pushingport 111 of the cylinder 5).

Because of the non-return valve 21, which is positioned before the legcontrol valve 22, the main pressure 17 can be switched off without thelegs 2 and 3 lowering. On roof convergence taking place, excess pressurein the legs 2 and 3 is bled to atmosphere by the the leg relief valve24.

When the legs 2 and 3 are fully set against the roof, the pressure inthe hydraulic circuit of the legs operates the pressure switch 68(FIGURE 4) such that its contact 123 is closed. As the contact 59 of thelimit switch 57 has also previously been closed (by operation of thelimit switch 57 upon the support unit being moved forward to itsrequired position), the current through switch 62 (i.e. from source 63,FIGURE 4) will be passed to the next support unit to be operated such asto energise its solenoid valve 163 and thereby initiate operation ofthat support. It will be seen, therefore, that the operation of the nextsupport is only initiated when it is proved that the legs 2 and 3 of thepreceding support has been fully set and that the preceding support hasbeen fully advanced.

In an emergency, the system can be controlled manually by the manualoperation screws 46 and 47. Operation of the manual operation screw 43on the leg control valve 22 will lower the legs 2 and 3, thus allowingthe support to move back if desired. Operation of the manual operationscrew 47 on the ram control valve 120 will allow the roof support unitto be moved forward or the face conveyor to be moved back, dependingupon the position of the leg control valve 22.

A further alternative circuit that can be used in the operatingconditions at a plough face is shown in FIG- URE 7. In this circuit theram control valve 120 in FIGURE 6 has been replaced by a ram pushcontrol valve 130 and a ram pull control valve 131. The operations ofthe solenoid valve 103 and the leg control valve 22 are the same asdescribed above for FIGURE 6.

The ram push control valve 130, which controls the pushing action of thecylinder is a two-position valve, with three main ports and two pilotports. In normal position (i.e. the position shown) of the valve 130 thereturn port 113 is blocked and the input port 1119 is connected to theoutput port 110 and thence to the pushing port 111 of the cylinder 5.When the pressure from pilot port 132 is released, the valve 130operates due to the main pressure always being applied to pilot port133. In the operated position of the valve 130 the input port 199 isblocked and the output port 110 is connected to the return port 113.This will step the pushing forward of the face conveyor. The valve 130will remain in its operated position until the pressure at the pilotport 132 creates a force great enough to overcome that due to pressureat the pilot port 133. The valve 130 will then return to its normalposition.

The ram pull control valve 131 which controls the pulling action of thecylinder 5, is a two-position valve, with three main ports and one pilotport. In the normal position (i.e. the position shown) of the valve 131the output port 114 is connected to the return port 134 and the inputport 135 is blocked. On applying a pilot pressure to the pilot port 136,the valve 131 operates so that the return port 134 is blocked and theinput port 135 is connected to the output port 114 and thence to thepulling port 112 of the cylinder 5. On releasing the pilot pressure frompilot port 136, a spring 137 returns the valve 131 to its normalposition.

The operation of this circuit of FIGURE 7 can now be described. With thevalves 103, 22, 130 and 131 in their normal position, it can be seenthat the conveyor advancing pressure from the hose 19 is applied to thepushing port 111 of the cylinder 5 and that the main pressure from thehose 17 is applied to the legs 2 and 3 and to the pilot port 132 of thehydraulic valve 130.

When it is desired to move the roof support unit forward thesolenoid-operated valve 103 is energised in the manner described aboveand illustrated with reference to FIGURE 9. On becoming energised, thesolenoid valve 103 supplies a pilot pressure to the pilot cylinder 29 ofthe leg control valve 22 and to the pilot port 136 of the ram pullcontrol valve 131. This pilot pressure operates the leg control valve 22which releases the pressure from the legs 2 and 3 and also from pilotport 132 of the ram push control valve 130, thus allowing the ram pushcontrol valve 130 to operate. This stops the pushing action of thecylinder 5 and the ram pull control valve 131, which is now in itsoperated position, due to pilot pressure at pilot port 136, allows themain pressure to flow to the pulling port 112 of the cylinder 5, andthis pulls the roof support unit forward. When the roof support unit hasmoved forward to its required position, the limit switch 57 (FIGURE. 9)is operated such that the solenoid valve 103 is de-energised, and thisallows the leg control valve 22 and the ram pull control valve 131 toreturn to their normal positions. The

pulling action of the cylinder 5 now ceases, and the main pressure fromthe hose 17 is re-applied to the legs 2 and 3 and also to the pilot port132 of the ram push control valve 130. As the legs 2 and 3 come intocontact with the roof, pressure at the pilot port 132 creates a forcelarger than that due to pressure at the pilot port 133 of the ram pushcontrol valve 130. This valve now returns to its normal position, thusallowing a pushing action to be re-applied at cylinder 5.

The operation of the attendant electrical circuit (which is identical tothat shown in FIGURE 9) is the same as described above with reference toFIGURE 9. That is to say, when the support is proved fully set and thesupport proved fully advanced, operation of the next succeeding supportis initiated automatically.

The function of the non-return valve 21 and the leg relief valve 24 isthe same as described above for the circuit in FIGURE 6.

This system of FIGURE 7 can also be controlled manually in an emergencyby the manual operation screws 46, 137 and 138.

Operation of the manual operation screw 46 on the leg-control valve 22will lower the legs 2 and 3. At the same time it will cause the pushingaction of the cylinder 5 to cease if the main pressure at line 17 isswitched on. If the main pressure at line 17 is switched oif it willcause the roof support unit to move back.

Operation of the manual operation screw 137 on the ram push controlvalve 130 will stop the pushing action of the cylinder 5.

Operation of the manual operation screw 138 on the ram pull controlvalve 131 will move the face conveyor back if the manual operation screw137 is also operated at the same time. Operation of the manual operationscrew 138 will also move the roof support unit forward if the legs 2 and3 are released.

The circuit to be now described with reference to FIGURE 8 isparticularly suitable for installations requiring snaking of theconveyor.

In FIGURE 8 is indicated a horizontal hydraulic ram comprising acylinder 5 accommodating a piston rod 102 which is pivotal-1y connectedto an armoured flexible face conveyor (not shown). Also indicated aretwo legs 2 and 3 of a roof support unit but, again, any desired numberof such legs may be provided. A main pressure flexible hose 17 and areturn flexible hose 18 extend along the face. The arrangement alsocomprises a solenoid-operated valve 140 for leg control and ram pullcontrol, a ram push control solenoid-operated valve 141, a hydraulic legcontrol valve 142, a hydraulic ram pull control valve 143, a hydraulicram push control valve 144, a hydraulic leg relief valve 24, anon-return valve 21, and a hydraulic valve block 15 which is connectedto both ends of the cylinder 5 and to the legs 2 and 3 and to theflexible hoses 17 and 18 by means of flexible branch pipes indicated bysingle lines.

The valves 140 to 144 and valves 21 and 24 may either be formed ininternal passages of the block 15 or they may have separate bodiesmounted on block 15.

The solenoid-operated valve 140 which controls the application of apilot pressur to the hydraulic valves 142 and 143 is a three-ported,two-position valve and functions in the same way as thesolenoid-operated valve 103 in FIG' 6, i.e.

Normal de-energized state: Input 54 blocked, output 52 connected toreturn 53.

Operated position: Return 53 blocked, input 54 connected to output 52.

The solenoid valve 141, which controls the application of a pilotpressure to the hydraulic valve 144 is also a three-ported, two-positionvalve and functions in the same way as the solenoid-operated valve 140,the input port being 145, the output port 146 and the return port 147.The reason for having this second solenoid-operated valve 141 will bestated further on.

The hydraulic leg control valve 142, which in this case only controlsthe raising and lowering of the legs 2 and 3, is a two-position valvewith three main ports and one pilot port 148. It functions in the sameway as the leg control valve 22 in FIGURE 6, i.e.

Normal position: Return 149 blocked, input 150 connected to output 151.

Operated position: Input 150 blocked, output 151 connected to return149.

The hydraulic ram pull control valve 143 which controls the pullingaction on the cylinder 5 and also returns the ram push control valve 144to its normal position is a two-position valve with three main ports andone pilot port 152. It functions in the same way as the ram pull controlvalve 131 in FIGURE 7, i.e.

Normal position: Input 153 blocked, output 154 connected to return 155.

Operated positions: Return 155 blocked, input 153 connected to output154.

The hydraulic ram push control valve 144 controls the pushing action ofthe cylinder 5 and is a twoposition valve with three main ports andthree pilot ports. In its normal position the input port 156 is blockedand the output port 157 is connected to the return port 158. On applyinga pilot pressure to pilot port 15?, the valve operates (so long aspressure is not applied to pilot port 160 at the same time) so that thereturn port 158 becomes blocked and the input port 156 is connected tothe output port 157 and thence to the pushing port 111 of the cylinder5. The output port 157 is also connected to the pilot port 159. Thisconnection allows the valve 144 to be kept in its operated positionafter the pilot pressure at pilot port 159 has been released. (This isknown as self-holding) The valve 44 remains in its operated positionuntil the pressure at pilot port 160 creates a force great enough toovercome that due to pressure on pilot port 159; the valve 144 thenreturns to its normal position.

The electrical circuit for the arrangement shown in FIGURE 8, is shownin FIGURE 10. As can be seen from FIGURE the circuit incorporates thecoils 160 and 161 respectively of solenoid valves 140 and 141, a limitswitch 57 having contacts 58 and 5? which is similar to and performs thesame function as switch 57 of FIGURE 9, a pressure switch 68 which has asingle contact 123 and which is similar to and performs the samefunction as the pressure switch 63 of FIGURE 9, and a main switch 62controlling the supply of power from source 63. The circuit alsoincludes a selector switch 162 by means of which any one of the solenoidvalves 141, or none, may be energised.

The operation of the whole circuit shown in FIGURES 8 and 10 can now bedescribed. With the valves 140 to 144 in their normal position, it canbe seen that the main pressure from the hose 17 is applied to the legs 2and 3.

When it is desired to snake the conveyor the solenoidoperated valve 141is energised by setting of the selector switch 162 to supply current tothe coil 161. On becoming energised, the solenoid-operated valve 141supplies a pilot pressure to the pilot port 159 on the ram push controlvalve 144. This pilot pressure operates the ram push contro valve 144thus allowing the main pressure from the hose 17 to flow to the pushingside port 111 of the cylinder 5 and push the face conveyor forward.Because of the self-holding feature of the ram push control valve 144,the solenoid-operated valve 141 may be de-energized once the faceconveyor starts to move forward.

When the face conveyor has been moved forward to its required position,the solenoid-operated valve 140 is energised by closing switch 62. Onbecoming energised the solenoid-operated valve 140 supplies a pilotpressure to the pilot port 148 of the leg control valve 142 and to thpilot port 152 of the ram pull control valve 143. The leg control valve142 operates, thus releasing the pressure from the legs 2 and 3. The rampull control valve 143 also operates thus supplying a pilot pressure topilot port 160 of the ram push control valve 144, which now returns toits normal position. The main pressure from the hose 17 now flows to thepulling port 112 of the cylinder 5 and the roof support unit movesforward.

After the roof support unit has moved forward to its required position,the solenoid-operated valve is deenergised by opening of the contact 58upon actuation of the limit switch 57 when the support reaches its fullyadvanced position. This now allows the leg control valve 142 and the rampull control valve 143 to return to their normal positions. The pullingaction of the cylinder 5 now ceases and the main pressure from line 17is re-applied to the legs 2 and 3.

The use of the non-return valve 21 and the legrelief valve 24 is thesame as that described above for the circuit in FIGURE 3.

When the limit switch 57 is operated upon the support being fullyadvanced, not only is contact 58 opened but also contact 57 is closed.Further when the pressure switch 68 is operated upon the legs 2 and 3becoming fully set against the roof, current is then passed to the coilof solenoid valve 140 of the next support. With the energisation of thisvalve, the operation of the next succeeding support will be initiated.

In an emergency the system shown in FIGURE 8 can be controlled manuallyby the manual operation screws 163, 164 and 165.

Operation of the manual operation screw 163 of the leg control valve 142will lower the legs 2 and 3.

Operation of the manual operation screw 164 of the ram pull controlvalve 143 will either move the support forward or pull the face conveyorback, depending upon the position of the leg control valve 142.

Operation of the manual operation screw 165 of the ram push controlvalve 143 will either push the face conveyor forward or move the roofsupport unit back, once again depending on the position of the legcontrol valve 142.

It is found that on a coal face where this type of circuit (FIGURES 8and 10) is required, a number of the roof support units are required topush the face conveyor forward at the same time after the coal cutterhas passed them. It is found that a sufficiently powerfulsolenoidoperated valve for these circuits takes so much current, thatonly one may be energised at a time in an intrinsically safe circuit. Itis for this reason that self-holding valves are employed for ram-pushcontrol. Alternatively, use may be made of a slide valve with no returnspring, or any other type of valve possessing the characteristic that,upon the application of fluid pressure to one of its pilot ports, itwill move from the first of its two positions to the second and remainin that position after the removal of that fluid pressure, beingrestorable to its first position by the application of fluid pressure toanother pilot port.

As already mentioned, the solenoid valve 141 may be tie-energised assoon as the roof support unit starts to move the face conveyor forward.This then allows for another solenoid-operated valve 141 to be energisedand de-energised on another roof support unit, and so on in sequencealong the face. On a face with such roof support units it is not alwaysrequired for every roof support unit to have a double-acting cylinder 5,perhaps only every fourth roof support unit will need such adouble-acting cylinder. This being so, the solenoid-operated valve 141can be removed and replaced by a blanking plate when only a pullingaction is required from the cylinder 5.

If it is required not to have the front legs and the rear legs of a roofsupport unit connected to the same hose, the leg control valve can bereplaced by either:

(i) A front leg control valve and a rear leg control valve, or

l 1 (ii) A leg raise control valve and a leg release contro valve with asystem of non-return valves. These two alternative leg circuits apply tothe arrangements shown in any of FIGURES 68.

The pressure drops in the hydraulic circuits during operating cyclesWill obviously depend upon the character istics of the componentsinvolved. It is to be understood that, if convenient, restrictors may beinserted at various points in the hydraulic circuits to obtain thesequence of operations described.

The limit switches 57 shown in FIGURES 5, 9 and 10 may be replaced byposit-ion transducers, that is to say, electrical devices having onepart which can move relative to another part and whose output isdependent on the relative positions of the parts, one of the parts beingmounted on the cylinder and the other being mounted on or attached tothe piston rod 102. Such position transducers are of known constructionand are capable of giving an electrical output proportional to theextension of the ram. Such position transducers may be used with anelectrical circuit of any of a number of known kinds having thecharacteristic that a relay operates when the electrical input reaches apredetermined value. Preferably this value is adjustable. The relay hascontacts corresponding to the contacts 58 and 59 of the switch 57. Bysuitable adjustment the relay may then be made to operate when thesupport unit reaches the end of its advancing travel, or, if desired,when it reaches any other position.

Similarly, the pressure switches 68 may be replaced by proportionalpressure transducers used in conjunction with an electric circuit havinga relay with contacts corresponding to the contacts 67 and 69 or, as maybe required, one set of contacts corresponding to those 123. Byproportional pressure transducer herein is meant a pressure-voltage,pressure-current, or pressureother electrical characteristic transducerhaving the property that it gives an output electrical voltage, current,or other characteristic which is linearly dependent on the inputpressure. Such transducers are known and their specific constructionforms no part of the present invention.

We claim:

1. A mine roof support system comprising a plurality of extensible fluidoperated mine roof support units each having at least one support, theunits being arranged at spaced intervals along a mineral face foroperation in a predetermined sequence; anchorage mean-s common to allthe support units; at least one fluid operated jack associated with andconnected between each support unit and the anchorage means foradvancingthe associated support unit relative to the mineral face; a fluidpressure supply line for supplying operating fluid to the support unitsand jacks; control means associated with each support unit andresponsive to a control fluid pressure for controlling the operationalsequence of the associated support unit and its associated jack; and afluid pressure connection linking the control means of one support unitwith the control means of the next support unit in the sequence fortransmitting said control fluid pressure from said one support unit tosaid next support unit; each said control means including in saidconnection a first fluid flow shut-off valve for controlling the flow offluid through said connection, the Valve having a first shut-off memberwith a first position in which fluid flow through the connection isprevented and a second position in which fluid can flow through saidconnection and means actuated by the jack for moving the first shut-offmember from the first position to the second when the jack is in apredetermined operational position and a second fluid flow shut-offvalve in said connection for controlling the flow of fluid through theconnection, the second valve having a second shut-01f member with afirst position in which fluid flow through the connection is preventedand a second position in which fluid can flow through said connection,and a second fluid pressure connection between said support unit and thesecond valve for applying support unit pressure to the second shut-offmember to urge the latter from its first position to its secondposition.

2. A mine roof support system as claimed in claim 1, in which the commonanchorage is a conveyor arranged along the line of the mineral face.

3. A mine roof support as claimed in claim 1, wherein the control meansalso include a first hydraulic valve having two positions and a secondhydraulic valve having at least two positions, and wherein said systemincludes a first fluid conduit connecting said one support unit with thefluid pressure line, the first hydraulic valve controlling fluid flow inthe conduit and having a first position in which pressure fluid can besupplied through the first conduit to the supports and a second positionin which fluid flow is prevented and the pressure fluid can be releasedfrom the supports, a second fluid conduit connecting the secondhydraulic valve to the fluid pressure line; third and fourth fluidconduits connecting the second valve to the hydraulic jack the latterhaving a double sided piston, the second valve having a first positionin which pressure fluid can be applied through the third conduit to oneside of the jack piston and released from the other side of the piston,and a second position in which pressure fluid can be applied throughsaid fourth conduit to said other side of the piston and released fromsaid one side of the piston; and a fluid conduit means connecting thefirst and second hydraulic valves with said fluid pressure connectionwhereby the control fluid pressure acts on these valves to change themfrom their first to the second positions.

4. A mine roof support system as claimed in claim 1, wherein said firsthydraulic valve has resilient means for urging it into its firstposition and said second hydraulic valve has resilient means for urgingit into its first position, said fluid conduit means applying saidcontrol fluid pressure to both said first and second valves inopposition to said resilient means.

5. A mine roof support system as claimed in claim 3 wherein anadditional fluid conduit so connects said first flow shut-off valve tosaid first hydraulic valve, that when the first shut-off valve is in itsopen position the control fluid pressure is applied to the first valvein the sense aiding said resilient means to move said first hydraulicvalve from its second to its first position, thereby balancing theapplication of said control fluid pressure to said first hydraulic valvethrough said further fluid conduit and permitting said first hydraulicvalve to be returned by its resilient means to its first position thusre-setting the support against the roof.

6. A mine roof support system as claimed in claim 3 and comprising anadditional fluid conduit means connecting said second flow shut-offvalve to said second hydraulic valve, so that when the said second flowshutoff valve is in its open position said control fluid pressure isapplied to said second hydraulic valve in a sense aiding the action ofthe resilient means to move the valve from its second position to itsfirst position thereby balancing the eflFect of the control fluidpressure applied to the second hydraulic valve through the furtherconduit means and permitting said second hydraulic valve to be returnedto its first position by the resilient means.

7. A mine roof support system as claimed in claim 3 and comprising ahydraulic fluid pressure line operatively connected to said second valvewhereby in the first position of said second hydraulic valve fluidpressure can be applied from the second pressure line to the jack toadvance the anchorage connected to said jack.

8. A mine roof support system as claimed in claim 1 wherein a furtherfluid conduit connects the fluid pressure connection at a pointdownstream of the first flow control valve to the first hydraulic valvefor applying, when the first flow control valve is open, the controlfluid pressure to the first hydraulic valve in a sense tending to movesaid first hydraulic valve from its second to its first position therebybalancing the application of said control 13 fluid pressure applied tothe first hydraulic valve through the fluid conduit means to return thefirst hydraulic valve to said first position and thus re-setting thesuport against the roof.

9. A mine roof support system as claimed in claim 8 comprising furtherfluid conduit means connecting the fluid pressure connection at a pointdownstream of the second flow control valve with the second hydraulicvalve for applying to the latter, when the second flow control valve isin its open condition, the control fluid pressure in a sense tending tchange said second hydraulic valve from its second postion to its firstposition whereby the second hydraulic valve is returned to the firstposition.

14 References Cited by the Examiner UNITED STATES PATENTS 2,301,02811/42 Esch 60-97 2,698,517 1/55 Witt 60-97 FOREIGN PATENTS 1,190,5324/59 France.

781,643 8/57 Great Britain.

823,128 11/59 Great Britain.

EARL J. WITMER, Primary Examiner.

JACOB L. NACKENOFF, BENJAMIN HERSH, BEN- JAMIN BENDETT, Examiners.

1. A MINE ROOF SUPPORT SYSTEM COMPRISING A PLURALITY OF EXTENSIBLE FLUIDOPERATED MINE ROOF SUPPORT UNITS EACH HAVING AT LEAST ONE SUPPORT, THEUNITS BEING ARRANGED AT SPACED INTERVALS ALONG A MINERAL FACE FOROPERATION IN A PREDETERMINED SEQUENCE; ANCHORAGE MEANS COMMON TO ALL THESUPPORT UNITS; AT LEAST ONE FLUID OPERATED JACK ASSOCIATED WITH ANDCONNECTED BETWEEN EACH SUPPORT UNIT AND THE ANCHORAGE MEANS FORADVANCING THE ASSOCIATED SUPPORT UNIT RELATIVE TO THE MINERAL FACE; AFLUID PRESSURE SUPPLY LINE FOR SUPPLYING OPERATING FLUID TO THE SUPPORTUNITS AND JACKS; CONTROL MEANS ASSOCIATED WITH EACH SUPPORT UNIT ANDRESPONSIVE TO A CONTROL FLUID PRESSURE FOR CONTROLLING THE OPERATIONALSEQUENCE OF THE ASSOCIATED SUPPORT UNIT AND ITS ASSOCIATED JACK; AND AFLUID PRESSURE CONNECTION LINKING THE CONTROL MEANS OF ONE SUPPORT UNITWITH THE CONTROL MEANS OF THE NEXT SUPPORT UNIT IN THE SEQUENCE FORTRANSMITTING SAID CONTROL FLUID PRESSURE FROM SAID ONE SUPPORT UNIT TOSAID NEXT SUPPORT UNIT; EACH SAID CONTROL MEANS INCLUDING IN SAIDCONNECTION A FIRST FLUID FLOW SHUT-OFF VALVE FOR CONTROLLING THE FLOW OFFLUID THROUGH SAID CONNECTION, THE VALVE HAVING A FIRST SHUT-OFF MEMBERWITH A FIRST POSITION IN WHICH FLUID FLOW THROUGH THE CONNECTION ISPREVENTED AND A SECOND POSITION IN WHICH FLUID CAN FLOW THROUGH SAIDCONNECTION AND MEANS ACTUATED BY THE JACK FOR MOVING THE FIRST SHUT-OFFMEMBER FROM THE FIRST POSITION TO THE SECOND WHEN THE JACK IS IN APREDETERMINED OPERATIONAL POSITION AND A SECOND FLUID FLOW SHUT-OFFVALVE IN SAID CONNECTION FOR CONTROLLING THE FLOW OF FLUID THROUGH THECONNECTION, THE SECOND VALVE HAVING A SECOND SHUT-OFF MEMBER WITH AFIRST POSITION IN WHICH FLUID FLOW THROUGH THE CONNECTION IS PREVENTEDAND A SECOND POSITION IN WHICH FLUID CAN FLOW THROUGH SAID CONNECTION,AND A SECOND FLUID PRESSURE CONNECTION BETWEEN SAID SUPPORT UNIT AND THESECOND VALVE FOR APPLYING SUPPORT UNIT PRESSURE TO THE SECOND SHUT-OFFMEMBER TO URGE THE LATTER FROM ITS FIRST POSITION TO ITS SECONDPOSITION.